How to have retractable limbs
You could create your robot's basic armature, with all its limbs out. Parent the limbs bones to the body bone. When you'll parent the object to the armature, use the With Empty Groups mode then in Object Data &gt; Vertex Groups assign each part of the mesh to the group it is supposed to be part of.

Then in the Pose Library save the basic pose and save a second pose that will be the contracted pose, here I've scaled my bones on the X axis. Click on the &quot;+&quot; button to save a pose:

Now whenever you want you can recall the contracted pose (select it and click on the magnifying glass icon of the Pose Library) and keyframe it in the Dope Sheet: